<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>双双飞翼三栏布局</title>
    <style>
       .main{
           width:100%;
           height:500px;
           background-color: yellow;
           float:left;
       }
       .box{
            margin-left:200px;
           margin-right:300px;
       }
        .left{
            width:200px;
            height:500px;
            background-color: pink;
            float:left;
            margin-left:-100%;
        }
        .right{
            width:300px;
            height:500px;
            background-color: blueviolet;
            float:right;
            margin-left:-300px;
        }
    </style>
</head>
<body>
<div class="main">
    <div class="box"></div>
</div>
<div class="left"></div>
<div class="right"></div>

</body>
</html>